Chapter 6 Question Set
2. Does increasing the frequency of a wave also increase its wavelength? If not, how are
these quantities related?
Answer:
No. Increasing the frequency of a wave decreases the wavelength. The two are related by
the formula v = *f (velocity = wavelength X frequency).
10. Why are light waves able to travel through a vacuum whereas sound waves cannot?
Answer:
Light waves do not require matter t6o propagate while sound waves require some sort of
matter that is moved during their propagation. Light waves are electromagnetic waves while
sound waves are mechanical waves.
14. How are the directions of the electric and magnetic fields of an e-m wave related to each
other and to the direction in which the wave is moving?
Answer:
The directions of the electric and magnetic fields of an e-m wave are perpendicular to each
other and both are perpendicular to the direction in which the wave is moving.
20. (a) You are standing on a pier and want to spear a fish that swims by. Should you aim
above, below or exactly where the fish seems to be? (b) What if you are swimming
underwater and want to spear a fish?
Answer:
(a) You should aim below where the fish seems to be since the refraction of light as it
passes from the water to the air would cause the fish to appear closer than it really is.
(b) You should aim exactly where the fish seems to be since there is no medium change
for the light from the fish to go through as it gets to you.
24. A coin is placed at a focal point of a converging lens. Is an image formed? If yes, is it
real or virtual, erect or inverted, larger or smaller than the object?
Answer:
The image is real, inverted, and the same size as the object (see figure 6-43).
30. Describe the image the lens of the eye forms on the retina.
Answer:
Again, this is a converging lens so the image is real, inverted, and probably smaller than the
actual object unless it’s a small enough object and it’s placed right at the focal point.
38. Give two advantages that a telescopelens or mirror of large diameter has over one of
small diameter.
Answer:
The larger the lens or mirror, the more light it can capture to the brighter things will appear in
the image formed. Also, the greater the magnification possible for images far away.